Copying machine



D. F. ANDERSON ETAL 3,214,584

Oct. 26, 1965 COPYING MACHINE 2 Sheets-Sheet 2 Filed Aug. 8, 1962 WVE/V 70/25 Jaw/4w Ffl/vosesa/v Jnmas 6. MOXNESS Dan/m0 VIZ F04 5K5 5r United States Patent 3,214,584 COPYING MACHINE Donald F. Anderson, St. Anthony Village, James G. Moxness, North St. Paul, and Donald W. Folsire, St. Paul, Minn assignors to Minnesota Mining and Manufacturing Company, St. Paul, Minn., a corporation of Delaware Filed Aug. 8, 1962, Ser. No. 215,584 Claims. (Cl. 250--65) This invention relates to the copying of graphic intelligence and has particular reference to apparatus for rapidly producing, on sensitized copy-sheets, a succession of copies of a differentially radiation-absorptive graphic original. A more specific example of the utility of copying machines constructed in accordance with the principles of the invention is the thermographic preparation of multiple copies on chemically sensitized systems paper copy-sheets using as the graphic original a correspondingly chemically treated systems paper master sheet on which a preferentially radiation-absorptive image pattern has been hand-written, sketched, typewritten, drawn, printed or otherwise impressed.

The invention makes possible the rapid automatic preparation of large numbers of copies by a thermographic or heat-copying process involving the brief intense direct irradiation of an original having image and background areas which are differentially absorptive of the radiation employed while maintaining the original in close pressure-contact and in back-printing configuration with the copy-sheet.

The thermographic copying art has previously employed radiation-transmissive belt or equivalent means for carrying composites of printed originals and heatsensitive copy-sheets past a stationary source of intense radiant energy. Suitable heat-resistant transparent belts of adequate length, strength and uniformity are expensive, require frequent cleaning, and are diflicult to guide. The original and copy-sheet are free-floating, and elaborate equipment is required to establish and maintain accurate positioning. Attempts to make multiple copies using heat-sensitive systems papers, or with other heat-sensitive sheets in the back-print configuration, meet with further diificulties; the direct heat-conductive contact of the belt with the printed surface reduces the amount of heat normally available at the radiation-absorptive image-forming areas and makes necessary the use of radiation sources providing still higher intensity of radiation and hence requiring excessive power input.

Other known forms of thermographic copying equipment have likewise been found less than fully elfective for making copies with heat-sensitive systems papers, particularly when modified to provide for the rapid automatic production of large numbers of copies. In some the power requirements are excessive; in others the rate of production of copies is necessarily slow; or the process may not be fully automatic; or various other difliculties may be encountered.

The present invention provides a copying machine which is particularly suited to the automatic and rapid multiple copying on systems paper copy-sheets of originals having image areas imprinted on systems paper master sheets.

An example of typical systems papers useful in the copying machine here to be described includes a copysheet comprising a paper-like backing coated on the front surface with a composition including a metal soap such as silver behenate, and a master sheet comprising a paper-like backing coated on the back surface with a composition including an organic reducing agent for the metal soap such for example as methyl gallate. Suitable polymeric binders, e.g., ethyl cellulose, are com- "ice monly included, and may be plasticized, as with triphenylphosphate in the case mentioned, for purposes to be hereinafter described. The master sheet is first imprinted with a desired message on the front surface, the printed image and unprinted background areas being differentially radiation-absorptive. Brief exposure of the printed surface of the master sheet to intense radiant energy while holding the coated front surface of the copy-sheet in close contact with the coated back surface of the master sheet then causes localized. heating at the strongly radiation-absorptive printed areas and results in a visible change at corresponding areas of the copysheet. The procedure may be repeated with a number of additional copy-sheets.

The copy-machine of the present invention will now be more fully described in terms of an illustrative em bodiment and by reference to the appended drawing, in which:

FIGURE 1 is a partial front elevation, partially in section, and with portions cut away to show inner detail;

FIGURE 2 is a partial end elevation, partly cut away;

FIGURE 3 is a cross-sectional view of the copy machine taken at section 33 of FIGURE 1;

FIGURE 4 is a partial end elevation showing the drive assembly;

FIGURE 5 is a schematic representation of details of a control mechanism;

FIGURE 6 is an end elevation of a preferred clamp member, partly in section; and

FIGURE 7 is a detailed sectional view showing a cam and associated terminal portion of a clamp member.

As illustrated in the several figures, the mechanism is mounted on a base 10 and generally between end frame plates 11 and 12. Rods 13 and 14' are directly fixedly connected to the end plates, whereas line shaft 15, shaft 16 and drive shaft 17 are rotatively mounted in bearings 19 supported in the end plates. A substantially circular supporting shroud 18 is afiixed to rods 13 and 14.

Grooved rollers 21 are mounted on rod 13. Similarly, grooved rollers 22 are mounted on rod 14, rollers 23 on shaft 15, and rollers 24 on shaft 16. These rollers rotatively support a pair of parallel rings 25 having a common axial line. To the rings are attached ring gears 26 having the same external diameter but somewhat lesser internal diameter and meshing with spur drive gears 27 afiixed to drive shaft 17.

The rings 25 are directly interconnected solely by a rigid drawbar 30 which, together with the arcuate cam members 31, is affixed to the rings and ring gears as illustrated in detail in FIGURE 7. A flexible spring clamp member 32 is attached at its forward edge to the bar 30 and is provided at its rearward edge with a U-shaped channel 34suita ble for receiving and retaining an edge of a sheet of paperlike material such as a graphic original or master sheet.

At the lower portion of the mechanism as illustrated in FIGURE 1, and between the ends of the generally circular cross-section of the shroud 18 as more clearly shown in FIGURE 2, there is provided a metal print roller 40 surrounding a shaft 44, and rubbery compressible pressure rollers 50 and 51 surrounding shafts 15 and 16 respectively. The shaft 44 is rotatively supported in suitable bearings within cam members 42 which in turn are rotatively supported on stub shafts 43 affixed to the end frame members 11 and 12. A tension spring 45 is provided on each of the supporting cam members 42 to bias the print roller 40 against the pressure rollers 50 and 51.

A source of intense radiation comprising a reflector 52 having a truncated elliptical internal cross-section is disposed immediately above the surface of the print roller 40 between the pressure rollers 50 and 51, and concentrates the radiation from line filament lamp 53 through a. protective transparent quartz window 54 along a narrow path just above the central upper surface of the print roller.

For inserting a master sheet into the machine there is provided a fixed shelf 65 and a movable shelf 66, together with a feed assembly comprising an elongate resilient compressible pad 62 mounted on a half-core member 61 and on a rotatable shaft 60. A handle 63 is provided for rotating the shaft 60 through approximately one complete revolution. As illustrated in FIGURE 3, rotation of the shaft in the counter-clockwise direction and with the shelf 66 in the extended position as there shown advances a master sheet by frictional contact along the shelf members until its forward edge is forced into the open slot of the channel 34 of clamp 32 as the latter is held against the shroud 18 above the rod 13. Continued rotation then advances the eccentrically mounted pad 62 to the free position to permit advance of the clamp around the circular path established by the rings 25. A suitable stop member is provided for retaining the pad in such position during the copying operation. On completion, the clamp is returned to the same position on the shroud and the master sheet is removed by again rotating the eccentric pad 62, this time in the clockwise direction as illustrated in FIGURE 3. A suitable pad may be constructed of a polyurethane foam or sponge filler and a flexible vulcanized rubber friction cover.

As the draw bar 30 and clamp 32 are advanced by rotation of the rings 25, the trailing edge of the clamp slides along the outer surface of the shroud 18. The master sheet, after insertion into the clamp by the process just described, is to be likewise drawn along the surface of the shroud. The sheet is first folded to reverse position over the edge of the clamp by contact with the edge of the shelf 66. It is then further smoothed and pressed into conformity with the shroud and with the print roller by a pressure plate 58 carried by a holder 59 attached to the frame, as shown in FIGURE 3, and disposed just ahead of the roller 50 at the edge of the printing zone. Such a pressure plate may be a springy section of -mil Mylar" polyester film.

Adjacent the roller 50 there is provided a copysheet feed mechanism comprising a friction roller 71 supported on a shaft 70 and mounted above a paper stop or retaining wall 75. A shelf 76 extends forwardly of the u er edge of the wall to direct the copy-sheet into the nip between pressure roller 50 and print roller 40. A panel 72 extending from the lower edge of the stop wall 75 serves as a base for a spring 74 and a movable platform 73 on which a stack of copy sheets may be placed.

The completed copy is removed from the machine to tray 84 by mechanism including friction roller 81 mounted on shaft 80, and spring contact member 83 mounted on rigid base 82. The grounded spring contact 83 holds the copy-sheet into frictional contact with the rotating roller and also serves to remove any static charges which may have accumulated on the sheet.

The machine is conveniently driven by a motor, not shown, attached to the line shaft through a coupling 94. A chain or belt 96 interconnects double sprocket 93 on shaft 15, double sprocket 95 on shaft 16, and sprocket 92 on drive shaft 17, and is held taut by means of idler pulley 97. A similar belt 87 interconnects double sprocket 93 with sprocket 77 on shaft 70, and a belt 86 interconnects double sprocket 95 with sprocket 85 on shaft 80. The sprocket 92 is free to rotate on shaft 17, being connected to clutch 90 which is permanently attached to shaft 17 and in effect drives the spur gears 27. Actuation of the clutch 90 is accomplished through an actuating lever 91 thereon. This lever is controlled by the movement of a lever 35 pivoting about an axis 36 and operated by an electromagnet 37. The opposite end of the lever 35 is designed to connect with a cam 64 carried by the shaft 60, and provides a safety mechanism permitting actuation of the clutch 90 only when the inserting device for the master- 4 sheet is in the inoperative free position as shown in FIGURE 3.

Somewhat similarly, the sprocket 77 controls the rotation of the shaft 70 and feed roller 71 through a clutch 78 actuated by a lever 79. This lever is controlled by an escapement 55 movable through a pivot 56 on movement of the lever 57 when contacted by an adjustable cam 46 attached to a ring 25 and ring gear 26, as shown in FIG- URES l and 2, and providing for a single rotation of feed roller 71 for each full rotation of the rings 25. The feed roller is free to rotate when the clutch 78 is disengaged through contact of escapement 55 with lever 79.

The position of the movable shelf 66 is controlled by a cam 67 in cooperation with a cam dog 68 affixed to the end of the off-center half-core 61, as indicated in FIG- URE 2. With the pad 62 in the free position and away from the clamp 32 and shroud 18, the shelf 66 is held away from the rotating assembly and permits passage of the bar 30 and associated components. As the handle 63 and shaft 60 are rotated for the purpose of feeding a master-sheet into the clamp, the shelf 66 is first allowed to move toward the clamp and into the position shown in FIGURE 3, thereby to direct the master-sheet into the proper position for entry into the clamp channel, and is then again retracted to permit free passage of the drawbar and clamp.

The structure of the clamp is more fully illustrated in FIGURE 6. A thin, springy, strong flexible sheet, for example of 2-mil stainless steel plate, forms the major portion 32 of the clamp, being wrapped around the drawbar 30 at the forward edge and deformed into a smoothly ridged rearward edge 33. A channel member 34 having a U-shaped cross-section and of slightly thicker and less flexible sheet stock, e.g., of 3-mil stainless steel plate, fits over the ridged edge and is attached to the lower face of the sheet 32 along the edge of the channel member. The ridged edge 33 is under moderate pressure contact with the opposing inner face of the U-shaped channel. It will be seen that the insertion of an edge of a paper sheet must be against the resistance offered by the spn'ngy edge portion 33, which effectively retains the sheet during the subsequent folding. Thereafter, the sheet is held firmly in position both by the fold and by the springclamping action while the assembly is drawn in a forward direction. However the edge is easily removed from the clamp by the reverse action of the compressible pad 62 as hereinbefore explained.

A thermostat 48 is provided just beneath and in close proximity to the printing roller 40 for the purpose of controlling the temperature of the roller prior to start of the copying operation. A switch 47 is actuated by cam 46 and, together with suitable relays and controls, provides for the completion of a final cycle by releasing the the electromagnet 37 after a final copy has been made. It will be appreciated that additional switches, relays, controls, and other auxiliary components and circuitry are provided.

From the foregoing description taken in conjunction with the illustrative drawing it will be apparent that operation of the machine involves essentially the following sequence. A supply of copy-sheets is first provided on shelf 73 and a suitably imprinted master sheet at shelf 65 with the printed surface exposed. With the clamp in the position shown in FIGURE 3, the insertion lever 63 is turned through one revolution, thus causing the forward edge of the master to be inserted within the channel 34 of the clamp. Meanwhile a main control switch has been turned to the on position, starting the motor driving the line shaft 15 and thus causing rotation of pressure rollers 50, 51 and of print roller 40, and also bring the lamp 53 to full intensity. Under these condi tions the roller 40 is soon brought to moderately elevated temperature, and this temperature is maintained by automatically switching the lamp off and on as required,

under control of the thermostat 48. The resultant flashing of the lamp, indicating that full operating temperature has been reached, serves as a signal that the copying sequence may be initiated; or automatic controls may be provided for the purpose.

A print switch is next turned to the on position. The electromagnet 37 thereupon acts upon lever 35 to release stop 91 and, through clutch 90, to initiate rotation of drive shaft 17, drive gears 27, rings 25, and drawbar 30. The master sheet, as it is drawn past the raised shelf 66, is folded back over its clamped leading edge and loosely against the shroud 18, and is then more sharply folded and also smoothed out as it is drawn beneath the springy plate 58.

As the drawbar 30 approaches the print roller 40, the arcuate cam dogs 31 rapidly depress the cams 42 and then more slowly permit them to be raised again to position under the bias of spring 45. The motion is just suificient to permit the bar 30 to pass between the two pressure rollers and the print roller.

During the same period the cam 46 contacts the lever 57 to raise the lever 55, actuate the clutch 78, and permit the feed roller 71 to make a single revolution, thereby feeding a single sheet of copy-paper across the shelf 76 and into congruency with the master sheet just as the clamp-end 34 reaches roller 50. Under the tension supplied by the smoothing plate 58, the master sheet presses the copy-sheet against the print roller 40 and the two sheets remain in congruent contact. As the bar 30 passes roller 51, roller 40 is again permitted to return to position. The two sheets are thus together drawn across the print roller and beneath the reflector 52. The clamp 32 and its channel member 34 are sufliciently thin to pass between the print roller and the compressible roller 51 without difficulty. The length of the clamp 32 between the bar 30 and the channel member 34 is at least equal to the distance between the beam of radiation from reflector 52 and the contact between rollers 40 and 51.

Through suitable automatic switch mechanism the thermostatically controlled lamp cut-off circuit is rendered inactive during rotation of rings 25 and hence the lamp remains at full brilliance and the printed surface of the master sheet is subjected to brief intense irradiation as it passes through the printing zone.

Shafts .and 16 are rotated at the same speed, but roller 51 is of slightly larger diameter than roller 50 so that the master sheet is placed and maintained under tension across the print roller 40 and between rollers 50 and 51. The differential surface speed, and the tension imparted thereby, is sufficient to provide effective pressure-contact between master sheet and copy sheet while being insufficient to cause tearing or scuffing of the master sheet. This tension is of course relaxed at the trailing edge area of the composite as contact with roller 50 is lost, so that copying at such areas might be expected to be ineffective. It has been found, however, that with copy-sheets or master sheets containing suitable plasticized binder materials in the reactant coatings, the two sheets are lightly but sufficiently bonded together during compression between roller 50 and heated roller 40 so that they remain effectively in close pressure contact for at least a short time after the release of tension; and copies made with such materials show no loss of contrast or sharpness down to the extreme trailing edge of the sheet.

Following its passage through the print zone, the clamp assembly is drawn around roller 51 and along the remainder of the circuitous route established by the rings 25. The relatively sharp bend applied to the mastersheet during passage over roller 51, and the slight but eifective stiffness of the paper-like copy-sheet, cause the leading edge of the latter to be snap-released from contact with the master sheet and to follow a divergent path along the springy contact plate 83 and into contact with the ejection roller 81. The sheet is thus ejected into tray 84, and at the same time is relieved of any impressed static electrical charges by contact with the grounded metal plate 83.

The clamp and master sheet continue around the circular orbit of the rings 25, and the cycle is repeated, to produce the desired number of copies. The print switch is then manually or automatically turned to the off position. The mechanism completes its final cycle during which cam 46 contacts switch 47, now in active condition to disconnect the electromagnet 37 and permit the lever 35 to engage the clutch pin 91 and disconnect clutch thereby stopping the rotation of the drive shaft 17 and of the rings 25 and with the clamp 32 in the position shown in FIGURE 3. The action also releases the cam 64 on shaft 60. The lever 63 is noW returned to its initial position, the accompanying rotation of the pad 62 thus forcing the folded edge of the master sheet from the enclosing channel 34- and ejecting the sheet along the temporarily lowered movable shelf 66 and onto the shelf 65 for disposal. The machine is then ready for insertion of another master sheet and printing of further copies; or the master switch is turned to the off position t-hus dis-connecting the motor and lamp circuits and stopping the machine.

What is claimed is as follows:

1. In a copying machine suitable for the thermographic preparation on each of a succession of copysheets of copies of a master sheet having differentially radiation-absorptive image and background areas, in combination: a thin springy flexible clamp member supported along its forward edge on a rigid drawbar and having along its rearward edge a narrow forwardly open channel for receiving and retaining a folded leading edge of a said master sheet; a print roller and associated differential-speed pressure rollers defining a radiation zone; a source of intense radiation in said zone for briefly intensely irradiating said master sheet; feed means for placing a copy-sheet in congruency with said master sheet and in position to be retained in smooth heat-conductive pressure-contact therewith while in said radiation zone; means for circuitously advancing said drawbar and clamp member through said radiation zone; and means for separating said printing roller from said pressure rollers during passage of said drawbar.

2. In combination, flexible clamp means for receiving and retaining a folded edge of a paper-like sheet, rigid drawbar means for imparting forward motion to said clamp means, advancing means for carrying said drawbar means and clamp means through a continuous circuitous path and between opposing pressure-applying surfaces, and opening means for briefly separating said opposing surfaces to permit passage therebetween of said drawbar means.

3. A thermographic copying machine suitable for mak-- ing multiple copies of a paper-like graphic original having differentially radiation-absorptive image and background areas, said machine comprising, in combination: a pair of ring-like supports having a common axial line; a rigid drawbar connecting opposed points on said rings; a thin flexible clamp plate member attached along its forward edge to said drawbar between said rings and having a paper-receiving open-mouthed forwardly-facing U- shaped channel along its upper rearward edge; a circular section shroud member inwardly of said drawbar for supporting said clamp plate member at constant distance from said axial line between said rings; a pair of pressurerollers, and a print roller therebetween, disposed with axes parallel to said axial line and with the surface of said print roller intermediate the contacting surfaces of said pressure-rollers forming an indented continuation of the circular section of said shroud member; camming means for separating said print roller from said pressure rollers during passage of said drawbar therebetween; power-applying means for providing rotation about said axial line of said 'rings and for rotating said pressure rollers at dissimilar surface speeds for maintaining a said original under tension across the portion of said print roller therebetween; and irradiating means for briefly exposing said original, while in pressure-contact with said print roller, to said radiation at high intensity.

4. A feed and removal mechanism suitable for insertion of a leading edge of a sheet of paper into a fixedly supported clamp member having a narrow slot-like opening and providing moderate spring tension against said insertion, said mechanism including a rotatable shaft, an elastically compressible friction pad member eccentrically mounted along said shaft, handle means for rotating said shaft in either direction throughout essentially a single f-ull revolution, and guide means for directing a sheet of paper edge-wise toward said opening; said shaft and pad being so disposed with respect to said guide and clamp as to cause a sheet of paper supported on said guide means to be forced toward and with its leading edge into the opening of said clamp as the shaft is rotated in the feeding direction.

5. A copying machine suitable for making multiple copies on systems paper copy-sheets of a graphic original master sheet by a thermographic back-printing method involving brief exposure of said original to intense radiant energy while in close pressure-contact with said copysheet all as herein described, said machine consisting essentially of, in combination: a source of said radiant energy and, in position for exposure thereto, a print roller, and a pair of spaced differential-speed resilient-surface pressure rollers parallel thereto, the whole defining an exposure zone; a thin flexible clamp member having a forward edge and a rearward edge and including along said rearward edge a forwardly facing open paper-receiving channel'and being attached along said forward edge to a rigid drawbar, said flexible member being of a length not less than the arcuate distance along said print roller from said energy source to the second of said pressure rollers and being sufiiciently thin and flexible to pass through said zone against the pressure of said resilient rollers toward said print roller; drive means for advancing said drawbar around a circuitous path including said exposure zone, and associated camming means for separat ing said print roller from said pressure rollers during passage of said drawbar therebetween; insertion means for frictionally advancing a master sheet into forward edge engagement with said channel and including an eccentrically mounted resiliently compressible friction drive member, a paper guide member, and a rigid support member for supporting said clamp against pressure applied by said drive member; paper feed means for feeding sheets of copy-paper into congruency with a said master sheet at a position of entry to said exposure zone; paper withdrawal means for removing said sheets of copy-paper at a position of exit from said exposure zone and in essentially static-free condition and including a friction drive roller and a grounded conductive resilient pressure member biased toward said drive roller; and means for maintaining said print roller at moderately elevated temperature, and below the temperature required for said thermographic printing, during periods preceding the copying operation.

References Cited by the Examiner UNITED STATES PATENTS 539,127 5/95 Gump 24259 709,523 9/02 Stratton 24259 2,012,422 8/35 Fanger 24-66 2,257,490 9/41 Aberle 101-142 2,740,895 4/56 Miller 25065 2,903,546 9/59 OMara 25065 2,927,210 3/60 OMara 250-65 2,958,778 11/60 Miller et 31 250-65 RALPH G. NILSON, Primary Examiner. 

1. IN A COPYING MACHINE SUITABLE FOR THE THERMOGRAPHIC PREPARATION ON EACH OF A SUCCESSION OF COPYSHEETS OF COPIES OF A MASTER SHEET HAVING DIFFERENTIALLY RADIATION-ABSORPTIVE IMAGE AND BACKGROUND AREAS, IN COMBINATION: A THIN SPRINGY FLEXIBLE CLAMP MEMBER SUPPORTED ALONG ITS FORWARD EDGE ON A RIGID DRAWBAR AND HAVING ALONG ITS REARWARD EDGE A NARROW FORWARDLY OPEN CHANNEL FOR RECEIVING AND RETAINING A FOLDED LEADING EDGE OF A SAID MASTER SHEET; A PRINT ROLLER AND ASSOCIATED DIFFERENTIAL-SPEED PRESSURE ROLLERS DEFINING A RADIATION ZONE; A SOURCE OF INTENSE RADIATION IN SAID ZONE FOR BRIEFLY INTENSELY IRRADIATING SAID MASTER SHEET; FEED MEANS FOR PLACING A COPY-SHEET IN CONGRUENCY WITH SAID MASTER SHEET AND IN POSITION TO BE RETAINED IN SMOOTH HEAT-CONDUCTIVE PRESSURE-CONTACT THEREWITH WHILE IN SAID RADIATION ZONE; MEANS FOR CIRCUITOUSLY ADVANCING SAID DRAWBAR AND CLAMP MEMBER THROUGH SAID RADIATION ZONE; AND MEANS FOR SEPARATING SAID PRINTING ROLLER FROM SAID PRESSURE ROLLERS DURING PASSAGE OF SAID DRAWBAR. 